Sixteen-year-old Gracie Sullivan is book-smart and resourceful, but her 18-year-old sister, Danielle, is impetuous, self-involved and boy-crazy. As “The Highway” opens, they’re driving cross-country from their divorced mother’s home in Colorado to celebrate Thanksgiving with their dad — until plans change.

Over Gracie’s strenuous objections, Danielle detours toward Helena, Mont., to woo her boyfriend, Justin Hoyt, who doesn’t want her to come. Ronald Pergram, a long-haul trucker and sexual predator who calls himself the Lizard King, trails them through Montana in his Peterbilt semi. His “fun,” as he calls it, has been discovered by a couple of creeps who want to get in on the action.

When Danielle and Gracie vanish on their trip through the mountains, Justin calls his dad, Cody Hoyt, whom we first met as a swashbuckling, rule-breaking lawman in Box’s 2011 thriller, “Back of Beyond.” But when Justin reaches him, Cody is on a drunk after being fired from the Lewis and Clark County Sheriff’s Department for planting evidence.

Alarmed by Justin’s call, Cody quickly sobers up, and with the help of his ex-partner, a feisty but inexperienced investigator named Cassie Dewell, he sets out to track down the girls.

The result is a violent, tension-packed, well-written thriller spiced with Box’s vivid portrayal of the Western landscape that he loves. Along the way, Box also drops in surprising insights about the itinerant lives of long-haul truckers.

Box’s previous thrillers, most of them featuring Wyoming game warden Joe Pickett, have all featured strong, tough-talking male protagonists, but the heroes of this one are the underestimated Cassie, who proves to be both tough and resourceful, and the courageous Gracie, who keeps her head when her flighty sister falls apart.

“The Highway” is the second new thriller this year from the prolific Box, who seems to get better with every book.

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Bruce DeSilva, winner of the Mystery Writers of America’s Edgar Award, is the author of “Cliff Walk” and “Rogue Island.”